Time-dependent density functional theory for many-electron systems interacting with cavity photons.

Area of Science:

• Quantum Chemistry
• Theoretical Physics
• Materials Science

Background:

• Accurate modeling of many-electron systems interacting with quantized light fields is crucial for understanding phenomena in microcavities.
• Existing methods often struggle with the complexity of strong electron-photon coupling.

Purpose of the Study:

• To develop a time-dependent (current) density functional theory (TDDFT) for many-electron systems strongly coupled to quantized electromagnetic modes.
• To establish a theoretical framework for describing electron-photon interactions within a quantum cavity.

Main Methods:

• Construction of a Kohn-Sham system for solving self-consistent equations for noninteracting particles.
• Formulation of the electron-photon wave function as a unique functional of electronic density and photonic coordinates.
• Suggestion of approximations for exchange-correlation potentials.

Main Results:

• The electron-photon wave function is shown to be a unique functional of the electronic (current) density and expectation values of photonic coordinates.
• The proposed Kohn-Sham system allows for the calculation of these fundamental variables.
• The approach naturally extends to time-dependent density functional theory for systems coupled to a Caldeira-Leggett bath.

Conclusions:

• The developed TDDFT provides a new theoretical tool for studying quantum electrodynamics in microcavities.
• This framework offers a pathway to understanding open quantum systems with strong light-matter interactions.